Ask the Coach: How Much Should I Hydrate During a Run?

How do you ensure you are staying well hydrated during trail runs? Even my hydration pack doesn’t feel like it’s going to be enough for longer ones.

– Samuel Davies, Southsea, United Kingdom

Hydration is a tough nut to crack. Drink too little, and your pee will start to look like Coca Cola. Drink too much, and your insides will feel like a water balloon. Fortunately, by applying a few tips, you can find out what works for you.

Before every run, hydrate substantially—16 ounces of water about 20 minutes before, with a bit more for longer efforts. Ideally, you should have to pee about a half-hour in.

For a run up to 90 minutes, you shouldn’t need additional fluids. (Experiment first, because your body may respond differently.) We have evolved to tolerate long efforts without water, so don’t get addicted to taking your handheld on short runs unnecessarily.

Longer than 90 minutes, drink 16 to 24 ounces per hour from the start of the run, adjusting for conditions and your sweat rate. You can usually get up to 2:30 with one large handheld.

For runs over that, if you don’t have access to a clean water source, wear a pack that can hold a two-liter bladder and two 16-ounce handhelds. That gives you about 100 ounces, enough for at least four hours.

If you are going even longer, you have two options: a portable water filter or water-purification tablets. Both are effective, but only if you have access to running water.

Remember, for any run over two hours, you will need calories and may want to supplement with electrolytes. Get both at once with packets of energy-drink powder.

David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they wrote a book called The Happy Runner.

This article originally appeared in our June 2016 issue.